People generally prefer daylight over artificial light as their primary source of illumination. Everybody recognizes the importance of daylight in our daily lives. Daylight is known to be important for people's health and well-being.
In general, people spend over 90% of their time indoors, and often away from natural daylight. There is therefore a need for artificial daylight sources that create convincing daylight impressions with artificial light, in environments that lack natural daylight including homes, schools, shops, offices, hospital rooms, and bathrooms.
There has been significant development of lighting systems which try to emulate daylight even more faithfully. For example, such lighting systems are used as artificial skylights, which attempt to emulate natural daylight that would be received through a real skylight. To enhance the realism of the artificial skylight, the skylight solution is usually mounted in a recess in the ceiling, in the same way that a real skylight would be mounted.
One approach which has been proposed previously by the applicant is to create a blue (i.e. clear sky) appearance when looking at a skylight at an angle, for example 40 to 90 degrees, but still emit mainly white light in a beam directed parallel to the normal direction of the skylight surface, i.e. downward. This provides functional white light in a downward direction and more blue light at angles to the normal.
It has also been recognized that it would be desirable to enable the color temperature to be selectable or even to evolve over time, so that the evolution of the color point of natural daylight can be emulated, or indeed a specific color point can be selected. However, this requires a more complex light source and associated control system.